1. On April 23, 1918, Illinois Governor Frank O. Lowden announced the creation of the Illinois State Council of Defense, which was tasked with coordinating the state's efforts during World War I. The council was responsible for everything from promoting patriotic sentiment to conserving food and fuel.

2. April 23, 1972 was a significant day for the University of Illinois at Urbana-Champaign. It was on that date that the university's computer science department held the first public demonstration of the UNIX operating system, which would go on to become one of the most widely used operating systems in the world.

3. On April 23, 1934, notorious Chicago gangster John Dillinger made headlines when he escaped from the Lake County Jail in Crown Point, Indiana. Dillinger and his gang had previously robbed banks and committed other crimes in Illinois, and he was eventually gunned down outside a theater in Chicago on July 22 of that year.

4. In 1946, the Illinois state legislature designated April 23 as Paul Revere Day in honor of the famous American patriot who made his famous "midnight ride" in 1775 to warn colonists of approaching British troops. Revere was born on April 22, 1734, and his birthday is celebrated in several states as a state holiday.

5. April 23, 1909 was the opening day of the Chicago Cubs' first game at their new home stadium, Weeghman Park (which would later be renamed Wrigley Field). The Cubs won that first game against the Cincinnati Reds by a score of 3-1, and the stadium has been the site of many memorable moments in Chicago sports history ever since.